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331.
The frog optic nerve contains a major group of proteins at a molecular weight of 62K. These proteins are insoluble in nonionic detergents, reactive with a general antibody to intermediate filament proteins, and not labeled by ex vivo incubations of optic nerve. They were therefore considered neurofilament proteins. Axonal transport and enucleation studies were performed to characterize further the origin of these proteins. The results show that the 62K proteins are transported into the optic nerve at a very slow rate (0.1 mm/day). After enucleation, these proteins are substantially reduced in concentration to 20% of the control value at 13 weeks. The predominant neurofilament proteins of the frog optic nerve are 62K in molecular weight. These results are discussed in terms of the anatomy of the frog optic nerve and also contrasted to findings obtained for the goldfish optic nerve. 相似文献
332.
Anne Ojala 《Journal of phycology》1993,29(3):278-284
Effects of light and temperature on growth of two freshwater photosynthetic cryptophytes of different cell size were studied in batch cultures. For the smaller Cryptomonas 979/67, Steele's model and equation of Platt et al. described the relationship between growth rate and photon flux density (PFD), whereas a hyperbolic tangent function gave a better fit for the larger Cryptomonas 979/62. Maximum growth rates given by the three models were consistent with each other, but the hyperbolic tangent function gave slightly lower estimates. Maximum growth rates in relation to temperature were well described for both species by the model of Logan et al. The optimum temperature for growth for Cryptomonas 979/67 was ca. 24.5° C and 19.0° C for Cryptomonas 979/62. The lethal temperatures were 30.4° C and 23.1° C for 979/67 and 979/62, respectively. The estimated maximum growth rates were 1.38 div.·day?1 for Cryptomonas 979/67 and 0.87 div.·day ?1 for Cryptomonas 979/62. There were interspecific differences in photoadaptation strategies, as Cryptomonas 979/67 required relatively high PFDs to show net growth, whereas Cryptomonas 979/62 grew at lower irradiances. Cryptomonas 979/67 showed photoinhibition soon after the saturation point, but Cryptomonas 979/62 tolerated a much wider range of irradiance. From their growth responses to light, Cryptomonas 979/ 67 appears to be a stenotopic and Cryptomonas 979/ 62 a eurytopic strain. 相似文献
333.
334.
Peter J. Simons Robert A. J. Oostendorp Maarten P. R. Tas Hemmo A. Drexhage 《Cancer immunology, immunotherapy : CII》1994,38(3):178-184
Head and neck squamous cell carcinomas (HNscc) produce low-molecular-mass factors (low-M
r factors,M
r25,000), which are antigenically related to the immunosuppressive retroviral transmembrane envelope protein p15E. These P15E-related tumour factors are thought to be responsible for some immunological impairments found in these patients (particularly the defective monocyte chemotaxis). A sequential and functional homology has been reported to exist between a bioactive fragment of interferon (IFN) and the putative immunosuppressive region of retroviral p15E (CKS-17). In this study we investigated (a) a possible functional and structural relationship between p15E and IFN, and (b) the presence of and the relationship between p15E-related low-M
r factors and IFN in HNscc patients. We report the following results. (a) Recombinant human (rhu) IFN was able to inhibit monocyte chemotaxis. (b) The anti-p15E antibodies crossreacted with rhuIFN in a dot-blot technique, however, the anti-IFN antibodies did not crossreact with disrupted murine leukaemia virus (p15E source). (c) Low-M
r factors (n=8–11) prepared from the sera of HNscc patients, which inhibit the monocyte chemotactic responsiveness, could be adsorbed by the anti-p15E antibodies as well as by the anti-IFN antibodies. However, the abilities of the factors to adsorb to the two categories of antibodies (namely, anti-p15E and anti-IFN) did not correlate. (d) Immunohistochemically we found IFN-related epitopes, in almost all HNscc specimens studied (17/18), in locations distinctive from those of p15E-related factors. The anti-IFN antibodies used in this study mainly reacted with basal epithelial cells close to the basal membrane, the prickle and granular cells of the squamous cell carcinomas. The anti-p15E antibodies mainly reacted with corneal layers, the granular and prickle cells, and did not react with basal epithelial cells. Our findings suggest that the immunosuppressive factors produced by HNscc cells are heterogeneous and p15E- and/or IFN-related. 相似文献
335.
Correlated autoradiographic and ion-microscopic study of the role of iodine in the formation of “cold” follicles in young and old mice 总被引:1,自引:0,他引:1
Carole Mestdagh Marie-Christine Many Sylvain Halpern Colette Briançon Philippe Fragu Jean-François Denef 《Cell and tissue research》1990,260(3):449-457
Summary The role of iodine in the formation of cold follicles (not labeled on autoradiograms after radioiodine administration) was analysed in ICR female mice during aging and involution of thyroid hyperplasia, by use of light and electron microscopy and by comparing autoradiographic and analytical ion-microscopic images for the same follicle in serial sections. The proportion of cold and partly cold (displaying a patchy or ring labeling pattern on autoradiograms) follicles increased significantly during aging. This increase was more pronounced in old mice fed an iodine-rich diet as compared to mice fed a moderate iodine diet. Similarly, during goiter involution produced by refeeding iodine, the follicular heterogeneity of iodine metabolism was more accentuated with a high dose of iodine, regardless of the age of the mice. The follicular lumina of hot and cold follicles had the same concentration of stable iodine, as shown by analytical ion microscopy, and the cells of both types of follicles formed colloid droplets in response to TSH. Furthermore, when a goitrogenic treatment was induced in aged mice, some cold follicles persisted after 8 days, but all follicles resumed hot after 16 days. By analytical ion microscopy, 127iodine was also found inside thyroid cells of old mice, but the cytoplasmic patches of 127iodine were not labeled with 125iodine. They corresponded to lipofuscin pigments and secondary lysosomes, as observed in serial sections at the electron-microscopic level. This intracellular stable iodine could constitute a slow turnover compartment not used for hormone synthesis.Portions of this work were presented at the 15th and 17th Annual Meetings of the European Thyroid Association (Stockholm 1986; Montpellier 1988). This work was supported in part by the Association de la Recherche sur le Cancer (ARC) and a cooperative programme Communauté Française de Belgique-France 相似文献
336.
Hideya Hayashi Yutaka Fujii Kikuko Watanabe Osamu Hayaishi 《Neurochemical research》1990,15(4):385-392
Prostaglandin (PG)E2 9-ketoreductase, which catalyzes the conversion of PGE2 to PGF2, was purified from human brain to apparent homogeneity. The molecular weight, isoelectric point, optimum pH, Km value for PGE2, and turnover number were 34,000, 8.2, 6.5–7.5, 1.0 mM, and 7.6 min–1, respectively. Among PGs tested, the enzyme also catalyzed the reduction of other PGs such as PGA2, PGE1, and 13,14-dihydro-15-keto PGF2, but not that of PGD2, 11-PGE2, PGH2, PGJ2, or 12-PGJ2. The reaction product formed from PGE2 was identified as PGF2, by TLC combined with HPLC. This enzyme, as is the case for carbonyl reductase, was NADPH-dependent, preferred carbonyl compounds such as 9,10-phenanthrenequinone and menadione as substrates, and was sensitive to indomethacin, ethacrynic acid, and Cibacron blue 3G-A. The reduction of PGE2 was competitively inhibited by 9,10-phenanthrenequinone, which is a good substrate of this enzyme, indicating that the enzyme catalyzed the reduction of both substrates at the same active site. These results suggest that PGE2 9-ketoreductase, which belongs to the family of carbonyl reductases, contributes to the enzymatic formation of PGF2 in human brain.Special issue dedicated to Dr. Sidney Udenfriend. 相似文献
337.
Lipid globules were isolated and characterized both chemically and morphologically. They were composed mainly of triglyceride and free sterol, which accounted for over 90% of the total globule content. Smaller amounts of diglyceride, carotenoid, free fatty acid, phospholipid and protein were found. No sterol esters or monoglycerides were detected. Morphologically, the isolated lipid globules resembled the lipid globules in situ. They were spherical, 0.4–1.5 m in diameter and lacked a trilaminar membrane.Non-Standard Abbreviations PL
phospholipids
- TG
triglycerides
- FS
Tree sterols
- DG
diglycerides
- SE
sterol esters
- MG
monoglycerides 相似文献
338.
339.
Chanhee Kang 《Autophagy》2016,12(5):898-899
Autophagy and cellular senescence are stress responses essential for homeostasis. While recent studies indicate a genetic relationship between autophagy and senescence, whether autophagy acts positively or negatively on senescence is still subject to debate. Although autophagy was originally recognized as a nonspecific lysosomal degradation pathway (general autophagy), increasing evidence supports a selective form of autophagy that mediates the degradation of specific targets (selective autophagy). Our recent study revealed distinctive roles of selective autophagy and general autophagy in the regulation of senescence, at least in part resolving apparently contradictory reports regarding the relationship between these 2 important homeostatic stress responses. 相似文献
340.